The invention relates to an infusion fusion pump for continually conveying a fluid, comprising an inlet, an outlet, a first piston movably supported in a first chamber, and a second piston movably supported in a second chamber. The invention relates in particular to an infusion pump, using which very small amounts of a drug can be applied precisely and with a constantly uniform flow or conveying rate.
EP 045 8114 B1 already discloses an infusion pump where using four valves two cylinders in each case equipped with a piston can alternately be filled with a drug from a reservoir and the drug can be drained by discharging the drug to the patient. Switching over the drug supply from a drained to a filled cylinder can achieve an approximately continuous conveying of drugs with relatively simple means.
A disadvantage of this infusion pump however is that due to the valve clearance an additional volume is created in the valve when the valve is opened, there being a reduced conveying of the drug. On the other hand, this reduced volume is displaced again when the valve is closed, resulting in increased conveying.
Over longer periods, the drug delivery corresponds to the therapy plan established by the physician. Under certain circumstances however, only a temporally brief under or oversupply of the patient with the drug conveyed by the infusion pump can—as a function of the drug—lead to the desired therapeutic success not being achieved.